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Units and Dimensions
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Units and Dimensions

Nikhil Mishra
Nikhil Mishra is an engineer and has been a Faculty of Physics in some of the most premier institutes of the country and has been involved

U
father,cats,birds,snakes, ethnic group
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I m akash gupta from JLN medical college, ajmer nd nikhil sir is my physics teacher in my pre medical stage nd i m greatly thankful to him... plyz follow him for best guidance in physics
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Teaching with complete enthusiasm like Nikhil sir is not everyone's cup of tea...I like the way he made us all feel physics...thank u sir
I am the student of Sir Nikhil. He is best physics teacher. Follow him to concept clearance & get better knowledge in physics.
Its nice... to have a teacher like as you its like as dream to study with u again sir....thnk u so much for teaching to us ????????
1. Units and Dimensions DIMENSIONAL ANALYSIS

2. Fundamental and Derived Quantities Experiments require measurements, and we generally use numbers to describe the results of measurements. Any number that is used to describe a physical phenomenon quantitatively is called a Physical Quantity. Physics is the study of Physical Phenomenonwith the help of the Physical Quantities. There are Seven Fundamental Physical Quantities namely Mass, Length, Time Temperature, Electric Current, Luminous Intensity and Amount of Substance. All other Physical quantities like Velocity, Momentum, Acceleration, Force etc. can be represented in terms of the seven Fundamental Physical quantities and are known as Derived Quantities Angle and Solid Angle are termed as Supplementary Quantities.

3. All the Derived Quantities can be expressed in terms of Fundamental Quantities and therefore the units of all the derived quantities can be expressed in the form of units of Fundamental Quantities The following table contains the Fundamental quantities with their SI Units S. No. Physical quantity 1. 2. 3. 4 5. 6. 7 Name of unit Symbol of unit Mass Length Time Temperature Luminous Intensity Candela Electric Current Amount of Substance Mole Kilogram Meter Second Kelvin Cd Ampere mol

4. The powers to which the fundamental quantities mustbe raised in order to represent a Physical quantity is known as dimension of that Physical quantity. For example Momentum can be represented in the form of Fundamental Quantities as p = mw therefore, is known as dimensional formula of momentum. m- M 1 LIT-1 Fundamental quantities cannot be written in the terms of other fundamental quantities. Mathematical constants like etc are dimensionless. Physical constants such as, 'Universal Gravitational constants (G)', 'Permittivity of Free Space (Eo Y etc. generally have dimensions. Pure ratios are always dimensionless and generally unitless but may not always be unitless. For example, Density is nitless and dimensionless wh reas Angle is dimensionless but not unitless, it has a unit Radian.